Most people won't really know the differences between PRC and Taiwan or for that matter Japan but since the idea might be adventure, character-building and what I'd describe as 'self-testing' (so its about assuring oneself they can do it) then Mainland China is probably the most challenging choice. I'd boast about that if I was a new graduate starting their first interviews. A Principal may very well like hearing a potential new hire saying "..after that hellish experience I came back and kneeled down and kissed the hallway floors of the first American/UK school I was in".

btw.. thats barely an exaggeration. We had an American High School public teacher here for ohhhhh about 3 weeks who got on the next flight to the USA promising to quite literally land in the US, get off the plane and kiss the ground lol